Species Unaspis euonymi - Euonymus Scale

one of 2 species in this genus in North America listed at nearctica.com

adult female 1.5-3 mm

adult male about 1 mm

Adult Female: covering brownish-gray, shaped like an oyster shell, broadly rounded posteriorly, tapering to a point anteriorly, with oval prosomal plate; body (only visible with covering removed) yellow, sac-like, pear-shaped, with 5 abdominal segments but no appendages or eyes

Adult Male: covering white, oblong or elongate, with middorsal and two lateral ridges; head yellowish-brown; body (only visible with covering removed) pale orange with wings

Nymph (Crawler): pale yellow to orange with no covering

many areas of the world

in North America, mainly eastern United States and southeastern Canada, but liable to occur anywhere via shipments of cultivated and ornamental plants

on leaves and stems of hostplant

nymphs and adults feed mainly on leaves of Euonymus species;

other hosts include boxwood (Buxus), Bittersweet (Celastrus scandens), English Ivy (Hedera helix), holly (Ilex), privet (Ligustrum), honeysuckle (Lonicera), Paxistima canbyi, and Pachysandra terminalis

overwinters as a fertilized female; one generation per year in the north, to three or four in the south; in early spring, eggs are laid underneath the protective scale, and hatch in May and June; crawlers migrate to leaves to feed; they may also be blown by the wind to other susceptible hostplants

U. euonymi is the most common and most serious pest found on Euonymus plants.

males and females of Unaspis citri are very similar (1, 2, 3) but their main host is Citrus, and they primarily attack the trunk and larger limbs; other hosts of U. citri include Annona muricata, Musa paradisiaca, Cocos nucifera, Psidium guajava, Ananas comosus, Artocarpus heterophyllus, Tillandsia usneoides

among other scale hosts on Euonymus, California Red Scale (Aonidiella aurantii) is reddish and circular, and Latania Scale (Hemiberlesia lataniae) is light brown and oval

close-up photos of males and females; PDF doc plus general overview (Ohio State U.)

live adult image of male and female U. euonymi on host plant (U. of California at Davis)

photo of female (North Carolina State U.)

11 photos of various life stages and hostplant damage (zipcodezoo.com)

drawings and overview of U. euonymi (North Carolina State U.)

drawings of adult female and male U. citri (Commonwealth Scientific and Industrial Research Organisation, Australia)

hostplants of scale insects in California with photos and overview of several specis (U. of California at Davis)

illustrated overview of biology and control (Missouri Botanical Garden)

description, hostplants, control (Ontario Ministry of Agriculture and Food)

diagnosis of genus; PDF doc with detailed description of microscopic anatomy (European and Mediterranean Plant Protection Organization)

problems and pests of Euonymus (Clemson U., Alabama)